A method for releasing a passenger restraint system is shown in 1141 Ingenieurs de l'Automobile (1982) No. 6, pages 69-72. Passenger restraint systems having one centrally located collision sensor perform relatively well in the event of a direct front end or rear end collision. However, such systems frequently encounter problems in collisions that occur at oblique angles with respect to the longitudinal axis of the vehicle. Oblique collisions, as opposed to direct front end or rear end collisions, commonly occur in city traffic. One problem experienced with oblique collisions, is that in spite of presenting an acute danger to the passengers, the passenger restraint system, such as a driver side air bag, is often released too late. As a result, the passenger may strike the steering wheel or dashboard of the vehicle before the air bag is released, thus negating the beneficial effects of the air bag and, indeed, possibly further injuring the passenger.
In German Patent No. DE-OS 22 40 389, a passenger restraint system is shown, which is provided to improve the responsiveness of the system to collisions occurring in an oblique direction, as compared to other passenger restraint systems. The system comprises two acceleration sensors that are oriented so that the sensitivity axes of the sensors are disposed at oblique angles with respect to the longitudinal axis of the vehicle. One disadvantage of this system, is that it is relatively expensive to manufacture and install the cabling for the sensors.
Other known passenger restraint systems comprise a plurality of sensors which are located in a decentralized arrangement on the vehicle. These systems likewise have high cabling expenses and, moreover, in the normal operation of the vehicle, they are very susceptible to disturbances. Other types of decentralized systems employ mechanical switches. However, the ability of mechanical switches to function properly during the operation of a motor vehicle in a collision cannot readily be checked.